The present invention relates to a tape cassette which is to be loaded on a magnetic recording and reproducing apparatus.
With a magnetic recording and reproducing apparatus and the like using a tape cassette, it is indispensable to the operation of the apparatus to load reels received in the tape cassette on the reel bases of the apparatus. The magnetic recording and reproducing apparatus considerably depends on smoothness, easiness and preciseness of the loading and positioning of the tape cassette on the apparatus for its over-all performance and handiness. Accordingly, various expedients have been done in connection with the shape of reels in the tape cassette and shapes of reel bases in the apparatus. Arrangement of reels in a prior tape cassette and prior reel bases, on which the reels are loaded, will be described hereinbelow with reference to several accompanying drawings.
Referring first to FIG. 1, there is shown a tape cassette 4 which receives therein a pair of reels 11 (one of which is illustrated). Each reel 11 includes a reel hub 3 with a magnetic tape wound therearound, an upper flange 2 and a lower flange 3a integrally formed with the reel hub 3, these flanges 2 and 3a being adapted to limit widthwise movement of the magnetic tape 1. A projection 3d provided centrally at the top of the reel hub 3 is biased by one end of a reel spring 5 in the widthwise direction of the tape cassette 4, the other end of the spring being secured to the tape cassette 4.
The reel hub 3 is formed at its lower end with an open ended recess which in turn is provided at its inner periphery with a plurality of radially extending pawls 3b. The pawls are adapted to engage with pawl pieces 8a of a pawl 8 (see FIG. 2) which is rotatable integrally with a body of the magnetic recording and reproducing apparatus. An abutment 3c extending beyond the lower flange 3a is formed at the lower, thicknesswise end of the tape cassette 4 for abutting against the reel base 10 provided on the body of the apparatus. The abutment 3c has a smaller diameter than that of an opening 4a formed at a lower portion 4' of the tape cassette 4.
The construction of the reel base will be explained with reference to FIG. 2 which permits the tape cassette as constructed in the above manner to be loaded on the magnetic recording and reproducing apparatus and a magnetic tape to run for recording and reproduction. In the drawing, reference numeral 10 designates a reel base rotatably mounted on a reel shaft 6 which is secured to a base plate 12 of the apparatus. A washer 13 is axially interposed between the reel base 10 and the reel shaft 6 of the base plate 12. A top end 10a of the reel base 10 constitutes an abutment surface for abutting against the abutment 3c of the reel hub 3 and limits height and inclination of the reel 11 relative to the base plate 12. A central, hexagonal column 10b of the reel base 10 is adapted to slidably engage the pawl 8 having a plurality of pawl pieces 8a which are adapted to engage with the pawl 3b of the reel hub 3. The engagement between the column 10b and the pawl 8 is assisted by a pawl spring 9. The pawl 8 is biased upward by the pawl spring 9 to be vertically moveable along the outer peripheral surface of the column 10b, and is limited in its movement by engagement with the underside of a reel cap 7.
In FIG. 3, a tape cassette is shown as being loaded on the reel base as described above. The abutment 3c of the reel hub 3 abuts against the top end 10a of the reel base 10 and is assisted by the biasing force of the reel spring 5 toward the reel base 10 to limit the height of the reel 11. In this position, the outer periphery of the reel cap 7 engages with the inner ends of the pawls 3b of the reel hub 3 to center the reel 11. The pawls 3b of the reel hub 3 engage with the pawl pieces 8a of the pawl 8 to permit the toque of the reel base 10 to be transmitted to the reel 11. A driving idler (not shown) for the reel base abuts against the reel base 10, as desired, to rotate the same.
In FIG. 4, the tape cassette 4 is shown in the course of being loaded on the reel base 10 whereupon the path along which the tape cassette 4 is moved onto the reel base 10 is not parallel to the reel shaft 6, but is inclined thereto or describes an arc. As seen from the drawing, the inner diameter of the pawl 3b is uniform in the axial direction of the reel 11 and the inner ends of the pawls 3b are fitted on the outer periphery of the reel cap 7, so that the inner ends of the pawls 3b abut against the outer periphery of the reel cap 7 in inclined relationship therewith to wedge thereonto. The path along which the tape cassette 4 is being loaded on the reel base 10 is influenced by the path of a cassette holder (not shown) which receives the tape cassette 4 and moves toward the apparatus. In this regard, the cassette holder becomes complicated in construction in order to correctly control the path of movement of the tape cassette 4. In the loaded position, the inner ends of the pawls 3b extend parallel to the axis of the reel shaft 6, and so the reel cap 7 should be guided parallel to the inner ends of the pawls 3b during the loading operation of the reel 11 onto the reel base 10. Thus the center of the reel 11 of the tape cassette 4 must be precisely aligned relative to the reel shaft 6 and accuracy must be maintained in association with the position of the tape cassette 4 in the cassette holder and the loading path thereof. In view of the fact that the pawls 3b engage with the reel cap 7 even when the tape cassette 4 is moved onto the reel base 10 slantwise, there may be conceivably provided an allowance for movement of the reel 11 in the tape cassette 4 in the thicknesswise direction. If such alowance were adequately provided, the tape cassette would be complicated in construction in order to maintain the positional accuracy of the reel 11 in the tape cassette 4. Accordingly, it has been desired to provide a tape cassette which permits a reel therein to be smoothly loaded on a reel base and to be accurately positioned thereon irrespective of the position of the tape cassette at the start of a loading operation thereof.